On Wed, 28 Dec 1994, Ron Torrella calmly sat reading what Michael Wathen wrote on Tue, 27 Dec 1994: > Then having a cap has to do more with the logistical approach to > achieving an end. A constant grain direction that is found on a > solid cap is in one manufacturer's domain a much easier medium to > layout, to set bearing, and to notch than a bridge that is > multi-laminate and has no cap. On the other hand, the other > manufacturer has no difficulty with the no cap alternative due to > a different type of tooling for notching and a entirely unique > approach to setting downbearing. In fact the cap is an added > frivolous step and a place where failure could lurk. A fact supported by.... > My own current belief is that one of the most vulnerable aspects > of the grand piano are all the joined and glued surfaces between > the string and the soundboard. Most of these surfaces consists > of mated unlike types of wood with differing expansion > coefficients. Not having a cap as one of these surfaces, in my > opinion, is the one thing that would keep an instrument longer at > its maximum sound production state. Perhaps you will explain, then, why a mid- to late-1970s vintage Baldwin's brigdecap (uncapped, just vertical laminations) shows more signs of torture today than an early 1900s Steinway's capped bridge. For that matter, why would an early 1900s _Baldwin_'s *capped* bridge show less visible strain (cracking, etc.) than the former uncapped Baldwin? Surely you're not accusing manufacturers (such as Baldwin and Steinway) of lacking the foresight/knowledge to realize that mating unlike woods will result in miserable bridgecap problems down the road? > I left a post on Pianotech some time ago entitled "Some Pianos > Just Die". And what I have said above is what I was hinting at > in that post. You consider a fine concert instrument where > everything is operating at its potential. Parts wear; you can > replace and voice hammers and strings..etc.... But you can't > keep that instrument as wonderful as it once was. You might even > replace the soundboard, dress the capo bar, replace agraffes. > The real failure is hidden just below the surface of the cap. > Every change of season tears at the glue bonds between the bridge > proper and the cap gradually changing it from a cohesive system > to one with loss of energy and loss of motion. Perhaps we should consider polymers in the construction of bridgecaps. It's a stable material. It's not as likely to split. It can be success- fully attached to the soundboard a number of ways. I'll bet the engineers could even come up with a mix that would have nearly identical properties of energy transfer as a good, solid multi-laminate bridge. If fact, I'll bet Young Chang or Samick is researching it as we speak (write)! The bridgecap isn't the only place one finds glue joints. What about the pinblock? The soundboard itself is a series of sticks of wood glued together side-by-side. By your reasoning, it would be better to have a soundboard constructed fashioned from a single piece of wood to avoid the treachery involved with glue joints. > Picture this... suppose you had need of a funny kind of train, > say, consisting of twenty some cars coupled together. At one end > you have the engine and at the other end you wish to receive some > kind of back and forth movement of the caboose. This requires > the engine to move back and forth and transmit its movement > across the twenty cars to reach the caboose. What type of > coupling would transmit the work done by the engine to the > caboose most efficiently? A loose coupling or a tight coupling? And the answer is..... Well, my guess is a tight coupling since energy could potentially be lost in a loose coupling. OTOH, in a tight coupling, there may be *some* distortion of energy since, at some point along the length of the train, there's bound to be some flexibility unless is was made up of some really high E steel. Wouldn't that flexing be considered a loss of energy? Seems to me that, in order for the various parts to do their thing, some sacrifices are going to have to be made. If that means the extra cap material will be slightly less efficient than the lack of it, then so be it. > With a cap things might look okay and you can expect the > downbearing force to hold cap in place. But you can never be > sure what the real situation is over time is unless you destring > and remove the bridge pins to find out how well it held up. Next > time you have a chance, check it out. Even so, short of hiring a forensics expert, how is one to determine which damage was a result of the downbearing force and which was the result of something else (like the destring process)? The Baldwin I recapped several years ago had an old bridge cap that was in astonishingly good shape considering its age and the environment in which it subsisted. I have the old cap hanging on the wall above my bench if anyone cares to drop by to have a look. (Removing it was necessary because -- in our humble, crude estimation the soundboard had sunk so much that even in the most humid months, the downbearing was quite negative. Yet, at the same time, the soundboard had plenty of crown. Go figure!) I have a customer with a much newer Baldwin (I'm almost positive it's mid- to late-70s) whose laminated -- uncapped -- bridge is splitting laterally (along *and* across laminates). Am I supposed to believe that this bridge is the better arrangement? The test of time seems to disagree. > Next, with a laminated capless bridge the individual laminates > can have glue failure between them but in the vertical plane no > failure has occurred between the string and the bottom of the > bridge. A delaminating bridge has it's consequences but it must > be quite severe in comparison to equal that of the cap failure. > The odd fact is that nearly every manufacturer makes a laminated > bridge. So why cap?? Are you suggesting that the integrity of the vertical plane is more important than the integrity of the horizontal plane in a bridge cap? While there may be no failure in the vertical plane one would think that horizontal and vertical properties must work together in order to provide the most efficient transportation from string to board -- thereby making one plane dependent on the other. If there is horizontal failure (side - side), wouldn't there be lost energy (taking into account the string's tendency to oscillate in a circular fashion)? I disagree with your assertion that the individual laminates can have glue failure between them but in the vertical plane no failure will occur between the string and the bottom of the bridge. Assuming that, over the years the pins have become grooved by string tension, if during a period of high humidity (ie. maximum expansion of the wood) the net bearing measured out negative on a laminated bridge which had developed cracks along and across the grain, wouldn't you begin to wonder about the integrity of the vertical plane? Isn't it possible that the downward motion of the soundboard as it dried out would cause the string -- resisting the forces of the soundboard -- to lift the pin out of its hole ever-so- slightly? A fully seated bridge pin is considered to be more efficient than an unseated, askew bridge pin, correct? Or perhaps you're suggesting that a pin that merely touches even one portion of its hole is sufficient for the transfer of energy. Phil Sloffer recently wrote: > > What I think is a more important question has > >to do with bearing. If you replace a sound board then this > >assumes that bearing is improved so my question is really about > >those situations where the old sound board is used. > >I know that some technicians will lower plates to get better > >bearing even if the sound board has little or no crown. I think > >this is wrong. I say leave the plate right where it is. Then > >the action will regulate OK. Any improvement in sound gained > >from lowering the plate will not last if the sound board is bad > >anyway. Put another way, if the old board sounds bad and it is > >decided to leave it in place then don't make other things worse > >by lowering the plate and making it impossible to regulate the > >action. I'm a little puzzled at how regulating the action comes into play in determining whether or not to lower the plate (seems like it would have to go down a mile before regulating would become a concern). Michael Wathen replied/queried: > What are they trying to achieve? It is as if everyone has agreed > you must have good downbearing for the instrument to sound good. > But no one has a clue as to how this could be true. Must be the heavy rhetoric that's clouding *my* mind....I believe I'll have some more eggnog. 8*) Cheers! Ron Torrella "Dese are de conditions dat prevail." School of Music --Jimmy Durante University of Illinois
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